Hard, thin films of hydrogenated, amorphous carbon (a-C:H), also called diamond-like carbon (DLC) films, can be created on metal surfaces by plasma-enhanced chemical vapor deposition (PECVD). Known PECVD processes which are used to create such films produce ions at low density (.about.10.sup.10 cm.sup.-3). The known processes generate plasmas with sheath thicknesses that are wide (0.5-1.0 cm) and do not conform to small surface variations in the substrate (.about.0.1 mm). Therefore, ions which are accelerated across the sheath in the known processes do so perpendicularly to the macroscopic surface of the substrate. Under these conditions, angled substrate surfaces, such as razor blade edges (which typically have a spacing of 100 .mu.m between the tips of blades in a stack), are subject to oblique fluxes of reactive ions. These conditions are believed to cause self-shadowing of some of the depositing species, leading to columnar growth of a-C:H films. It is also believed that the low plasma density yields a relatively low ion-to-atom ratio at the substrate surface. Deposition under conditions in which adatom surface mobility is poor, for example at low substrate temperatures (T/T.sup.melt &lt; 0.1) and low ion flux, is also believed to exaggerate columnar growth of a-C:H films on highly-angled substrates. Such columnar growth results in films which contain voids and grain boundaries, and exhibit poor mechanical strength. Columnar growth is observed in PECVD of a-C:H films in low-density RF capacitively coupled plasma reactors on highly-angled substrates such as razor blades.
The known approaches also suffer from low deposition rates. The low electron density of the known approaches does not effectively dissociate the hydrocarbon feed gas. Therefore, the number of precursor molecular fragments in the low density plasma is low. For example, typical deposition rates for capacitively coupled plasma PECVD of a-C:H are in the order of 20 nm/minute. These low deposition rates hinder processing throughput and result in low profitability for the process.